Although a wide variety of highly effective, aqueous, iodine-containing germicidal solutions are known and extensively used against a broad spectrum of microorganisms, their commercial application is attended by certain disadvantages inherent in the chemical nature of their principal component, iodine.
In the first place, since iodine is volatile, iodine-containing germicides in the form of either powders or solutions tend to lose iodine by sublimation and evaporation. Accordingly, the germicides are characterized by shelf lives of restricted duration.
In the second place, because of its extreme activity, the iodine tends to react with other ingredients of any aqueous germicidal composition in which it is contained, causing the composition to lose germicidal activity. By-products of such reactions, notably hydriodic acid, compound the problem because of their own per se chemical activity.
The general problem with the available aqueous iodine germicidal preparations is their instability, slowly but inexorably iodine in solution oxidizes the solvating co-ingredients such as ethanol in Tincture of Iodine, polyvinylpyrollidone in Betadine, and ethyleneoxides and alcohols in nonionic detergents such as Wescodine.
The iodide generated by these reactions ultimately forms the triiodide ion which will not penetrate microbial cell walls. It therefore is ineffective as a germicide.
Furthermore, iodine preparation such as those listed above cannot be co-mingled with other materials such as phenols and quaternary ammonium detergent germicides, or other chemically reactive substances. If so co-mingled, the undesirable degenerative reactions noted above occur and destroy the expected benefit of the co-mingling materials.
It has been proposed (Van Allen U.S. Pat. No. 1,661,640) to overcome the foregoing problem by preparing, storing and dispensing the iodophor in the form of a dry hygroscopic powder and then, just before the iodophor is to be applied, adding water to form the active germicidal solution.
The problem with this proposed routine is that the iodine compounds contained in the dry iodophor are extremely sensitive to the presence of water. The degradative reactions noted above are catalysed by the presence of only minute amounts of that substance.
In practice, the germicidal composition is exposed to water derived from two sources.
In the first place, it is impossible to exclude all traces of moisture from the containers in which the compositions are to be stored. This ambient moisture, even though present in minute amounts, suffices to initiate the reactions, by which the iodophor is converted to undesirable products.
In the second place, the reaction, once initiated, is auto-catalytic since it produces water as a product. This endogenous water further promotes the undesirable degradation reactions, which accordingly take place at an ever-increasing pace.
Nevertheless, in spite of these disadvantages, iodine is an extremely effective and widely used germicide. It has an impact on the entire spectrum of microorganisms including the human pathogens. Bacteria, both gram negative and gram positive; rickettsia, fungi, viruses and protozoan organisms all are effectively destroyed after exposure to dilute iodine solutions.
It accordingly would be desirable, particularly for military purposes, to provide in commercial form an iodine source, i.e. a light weight "pre-iodine", which is easily contained, stored and transported; which is stable and has infinite shelf life; which is compatible with selected supplemental germicides; but which, upon the addition of water, is converted instantly to a germicidal composition containing nascent Iodine and evidencing all of the desired germicidal qualities, making it useful in the usual applications to which iodine germicides are suited.
The foregoing and other objectives of my invention are achieved by the provision of a solid, storage-stable, germicidal, pre-iodine composition which, broadly stated, comprises a solid oxy-compound of iodine; a solid, water soluble, chemical reducing agent therefor; and a solid desiccant.
The oxy-compound of iodine furnishes the iodine content of the ultimate germicide. The reducing agent provides the means of unlocking the iodine from the oxy-compound of iodine when the composition is placed in water. The solid desiccant shields the other two components from the deleterious action of ambient or endogenous moisture to which they may inadvertently be exposed during the storage cycle.
In addition to the foregoing key ingredients, there may be incorporated in the composition suitable proportions of buffering agents to regulate the pH, solvating agents to increase the solubility of the components in water, and compatible co-germicides.
There thus is provided a pre-iodine composition which may be stored indefinitely in the solid form, but which upon the addition of water becomes instantly activated to generate a germicide containing elemental iodine and possessed in maximum degree of the desirable properties of germicides of this class.